Some 1,3-dithiolene derivatives have been known to these dates. For example, U.S. Pat. No. 3,057,875 discloses that certain 2-methylene-4,5-dicyano-1,3-dithiolene derivatives represented by the following formula (i) are useful as ultraviolet absorbents: ##STR1## wherein A and B are individually a group .dbd.CN, --COOR or --SO.sub.2 R (R: alkyl group or the like), and the like.
It has also been disclosed in Japanese Patent Publication Nos. 18576/1981, 18577/1981, 18578/1981 and 18579/1981 (Corresponding to U.S. Pat. Nos. 4,080,467; 4,080,466; 4,022,907 and 4,035,387) that some other 1,3-dithiano derivatives represented collectively by the following general formula (ii) are useful as therapeutic agents for hepatopathy of human and animal: ##STR2## wherein R and R.sup.1 denote individually a lower alkyl group or an alkoxyethyl group; X and X.sub.1 each denote oxygen or sulfur atom, n is an integer of 0, 1 or 2; and A means a group --CH.sub.2 --, --(CH.sub.2).sub.2 ----(CH.sub.2).sub.3 --, --(CH.sub. 2).sub.4 --, --CH.dbd.CH--or--CH(OR.sub.2)--CH.sub.2 --where R.sub.2 acetyl or propionyl. In addition, the use of 1,3-dithiano derivatives as fungicidal agents of agricultural and horticultural utilities is described in Japanese Patent Publication Nos. 34126/1972 and 34883/1976. Japanese Patent Application first publication "Kokai" No. 34852/1984 or U.S. Pat. No. 4,564,627 also discloses use of them as feed additives which reduce the amounts of the internal fat as accumulated and deposited in the abdominal cavity or peritonea of cattle, poultry, fish and the like and improve the eggshell strength of poultry.
The 1,3-dithiolene derivatives disclosed in the above-mentioned U.S. Pat. No. 3,057,875 do not show any physiological activities as agricultural chemicals and medicines. An object of this invention is to provide novel and useful 1,3-dithiano derivatives which are different from the known 1,3-dithiano derivatives and have remarkably useful activities as fungicidal agents of agricultural and horticultural applications and therapeutic agents for treating the hepatopathy. Another object of this invention is to provide 1,3-dithiano derivatives useful as excellent agents for reducing the internal fat of animals.
Some of the 1,3-dithiano derivatives described in the above-mentioned Japanese Patent Publication Nos. 34126/1972 and 34883/1976 have already found wide-spread utility as fungicidal agents for the control of rice blast (Pyricularia oryzae). When they are applied by the folier treatment, their controlling effects against rice blast (Pyricularia oryzae) may vary depending on environmental conditions and may not be able to provide steady, controlling effects in some instances.
In recent years, a feed of high-fat content and high-carbohydrate content is usually given in large amounts to cattle, poultry, cultivated fish, etc. so that they are caused to grow in shorter periods of time at small confined places under intensive care prior to their delivery to the market. As a result, fat tends to accumulate and deposit excessively in the bodies of these animals, especially, in their abdominal cavity or peritonea.
This means inefficiency in the conversion of nutrients in the feed given to animals into proteins which form edible meat parts of cattle and poultry. Carcass obtained from such animals having the excessively accumulated abdominal fat tends to have an unduly high fat content. This certainly does not meet the recent preference of consumers. More and more consumers are hence hesitant to buy the meat of high fat content obtained from the cattle, poultry and cultivated fish, which have been raised under such intensive care. This has led to a serious problem such as lowered demand.
When the known 1,3-dithiano derivatives described in the above-mentioned Japanese Patent Publication No. 18576/1981 through 18579/1981 and Japanese Patent Application first publication "Kokai" No. 34852/1984 (corresponding to U.S. Pat. No. 4,564,627) are administered to men as therapeutic agents for hepatopathy or are added to feed and administered to animals, some adverse effects may be given depending on the health conditions of animals or the manner of administration.
It is hence another object of this invention to solve the above-described problems in the various fields and to provide novel and highly-useful 1,3-dithiol-2-ylidene-alkylsulfonylacetic acid alkyl esters which can substitute for the known 1,3-dithiano derivatives.